1. Field of the Invention
This invention relates to magnetic tape recording heads, and more particularly to a compression zone recording head.
2. Description of the Related Art
In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly referred to as magnetic heads. Data is written on the magnetic recording media by moving a magnetic recording head to a position over the media where the data is to be stored. The magnetic recording head then generates a magnetic field, which encodes the data into the media. Data is read from the media by similarly positioning the magnetic read head and then sensing the magnetic field of the magnetic medial. Read and write operations are independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has lead to increasing the track density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. This movement generally entrains a film of air between the head and tape. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in intimate or near contact with the tape to effect efficient signal transfer, and so that the read element is in intimate or near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element. The conventional head contour comprises a cylindrical or complex shape which is critical in maintaining the moving tape at the desired spacing from the head. The contact, or near contact, spacing is maintained by controlling the contour shape to “bleed”, or scrape the boundary layer of air carried by the tape away and into bleed slots before encountering the transducer to prevent the tape from “flying”, or losing contact with the transducer.
Alternatively, the contour is designed with a small radius and a high wrap angle so that high pressure is exerted on the head while the tension is low. However, the contour of the head must be such that the pressure exerted by the tape on the transducer is not so high that the surface of the transducer wears excessively. Heads are often provided with outriggers on both sides of the head which help support the tape and reduce head wear, but, more importantly, control the wrap angle of the tape with respect to the head. Any change in radius will change the pressure of the tape on the head at the same tape tension.
A flat contour thin film tape recording head for a bi-directional tape drive is described in commonly assigned U.S. Pat. No. 5,905,613 to Biskeborn and Eaton which is incorporated by reference herein. The flat contour head comprises a flat transducing surface on a substrate having a row of thin film transducers formed on a surface on one side of the substrate which forms a gap. The substrate with the row of transducers is called a “rowbar substrate”. The transducers are protected by a closure of the same or similar ceramic as the substrate. For a read-while-write bi-directional head which requires that the read transducer follows behind the write transducer, two rowbar substrates with closures are mounted in a carrier facing one another. The recording tape overwraps the corners of both substrates with an angle sufficient to scrape the air from the surface of the tape and not so large as to allow air to reenter between the tape and the transducing surface after the tape passes the corner. By scraping the air from the surface of the moving tape, a vacuum forms between the tape and the flat transducing surface holding the tape in contact with the transducing surface. At the corners of the substrates, bending of the recording tape due to the overwrap results in separation of the tape from the transducing surface for a distance that depends on the wrap angle, the tape thickness and the tape tension. The transducers must be spaced from the corners of the substrate at a sufficient distance to allow the vacuum between the tape and the transducing surface to overcome this separation.
There is an ongoing need for reduced separation of the transducers and the recording media and of improved control and reliability of this separation in order to support constantly increasing data density and speed requirements of data storage systems. The present invention provides an improved recording head to address this need.